Device for sealing a passage through a wall

ABSTRACT

The invention refers to a device for sealing a passage ( 1 ) through a stationary wall ( 2 ) between a first space ( 3 ), which is arranged to contain a liquid. A rotatable shaft ( 5 ) is intended to extend in the passage through the wall in such a way that a gap is formed, which extends around the shaft between the shaft and the wall. A chamber ( 8 ), containing liquid, is arranged between the gap and the first space and extends around the axis. A rotatable disc ( 14 ) is fixedly arranged on the shaft and exends outwardly from the shaft into said chamber. Means ( 17′, 17 ″) are arranged to force the liquid in the chamber to rotate at a rotary speed substantially exceeding the rotary speed of the shaft.

THE BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention refers to a device according to the preamble ofclaim 1, and a method according to the preamble of claim 25. Theinvention is particularly suitable for sealing between a substantiallystationary wall and a rotating shaft extending through a passage in thewall. Examples of application areas are ships and a propeller shaftextending through the hull of the ship. Also other application areas arepossible.

DE-A-1955016 discloses such a device for sealing a passage through awall between a first space, which is arranged to contain a gas, and asecond space, which is arranged to contain a gas, and a second space,which is arranged to contain a liquid. A rotating turbine shaft extendsin the passage through the wall and is journalled in a shaft bearinghaving a gap extending around the shaft between the shaft and the wall.A rotating disc is rigidly arranged on the shaft and extends outwardlyfrom the shaft. A stationary wall in the form of a further disc isprovided between the shaft bearing and the rotating disc. The stationarydisc is designed in such a way that it forms a space between the twodiscs. Furthermore, supply conduits are provided for the supply ofliquid to this space via two nozzles. The liquid forms a rotating liquidring in the space.

DE 4212169 discloses a labyrinth sealing having a channel between arotating part and a stationary disc. The channel may be supplied withoil via a supply channel, wherein a liquid level will be formed in thechannel due to the rotation of the disc.

GB 1284596 also discloses a labyrinth sealing with feeding of liquidinto a space formed by flange members from a rotating rotor. Astationary disc extends into the space and includes channels for saidfeeding of liquid and for discharging liquid from the space.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device enabling asufficient sealing of a passage for a rotating shaft.

This object is achieved by the device initially defined, which ischaracterised in that it includes means arranged to force said liquid inthe chamber to rotate at a rotary speed which substantially exceeds therotary speed of the shaft.

By such means it is possible to ensure in an efficient manner thatsubstantially no liquid will be transported from the second space to thefirst gas-filled space. The liquid, which rotates at the rotary speedwhich is higher than the speed of the shaft, forms a liquid body in aradially outer part of the chamber. This liquid body preventssubstantially all media transport through the passage. In relation tomechanical sealings the advantage of a low friction and substantially nowear of essential sealing components is of course also achieved.Advantageously, the wall is stationary and consists, for instance, of awall element of a ship or a stationary plant.

According to an embodiment of the invention, the chamber is arranged topermit that a part of said liquid flows into the chamber and at leastpartly is retained in the chamber for said sealing of the passage.Consequently, the liquid proper to be sealed off will form a sealingliquid body which prevents said media transport through the passage.

According to a further embodiment of the invention, said means arearranged to provide said rotation in the chamber between the disc andthe first space. Consequently, the rotating liquid body is formed in anouter part of the chamber between the disc and the first space. The discwill thus prevent liquid from flowing straight forward from the secondspace to the first space. The liquid will instead be forced to theradially outer part of the chamber, i.e. to the blocking liquid body.

According to a further embodiment of the invention, said means include ablade member arranged to rotate independently of the shaft. By such ablade member the desired rotation may be achieved in an efficientmanner. Advantageously, said means include a drive member, which isarranged to rotate the blade member at a rotary speed which is higherthan the rotary speed of the shaft. The blade member may be rotatablycarried by a bearing member which is connected to at least one of theshaft, the disc and the wall.

According to a further embodiment of the invention, the blade memberincludes at least one set of blades which are arranged in the chamber.Advantageously, the blade member may include a rotor member whichextends outwardly in the chamber. The rotor member may include one ortwo such sets of blades. One such rotor member may be annular and extendaround the shaft, wherein the blades are arranged on the rotor memberand uniformly distributed around the shaft.

According to a further embodiment of the invention, the blade memberincludes a first set of blades, which are arranged on the rotor memberand turned towards the first space, and a second set of blades, whichare arranged on the rotor member and turned towards the disc.

According to a further embodiment of the invention, the rotor memberincludes a rotor of an electric motor having a stator which is providedoutside the chamber. The stator and the electric connections may thus belocated outside the chamber and in the first space.

According to a further embodiment of the invention, the blade memberforms the chamber. The blade member may then advantageously include afirst set of blades, which are arranged on a first limiting wall of thechamber and turned towards the disc, and a second set of blades, whichare arranged on a second limiting wall of the chamber and turned towardsthe first limiting wall.

According to a further embodiment of the invention, said means arearranged to supply liquid to the chamber at such a speed and directionthat the liquid in the chamber is forced to said rotation. Such meansmay include at least one nozzle for said liquid supply, wherein saidnozzle extends in a substantially tangential direction into the chamber,and a pump for providing said liquid supply.

According to a further embodiment of the invention, the chamber includesseveral part chambers, which are arranged between the gap and the firstspace, and extend around the shaft, and two rotatable discs, which arerigidly connected to the shaft and extend outwardly from the shaft in arespective one of said part chambers, wherein each of said part chambersis arranged to contain liquid. Advantageously, said part chambers may bearranged to permit a part of said liquid to flow into the part chambersand at least partly be retained for sealing of the passage.

According to a further embodiment of the invention, the device isarranged to permit liquid to flow from the chamber to the second space.In such a way it is ensured that liquid not may flow from the chamberinto the first space. The device may then include a wall portion, whichpartly defines the chamber and extends outwardly from the gap. Thechamber may, between the disc and the wall portion, form an outletchannel, which is arranged to reduce the speed of the liquid flowingfrom the chamber to the second space. In such a way it is possible toregain pressure and thus reduce the energy consumption of the device.The outlet channel may extend from a radially outer position at theperiphery of the disc to a radially inner position in the proximity ofthe shaft. In order to further increase the pressure recovering, guidevanes may be arranged in the outlet channel for conveying the liquidflowing from the chamber to the second space. Advantageously, said guidevanes are arranged on the wall portion.

The object is also achieved by the method defined in the independentclaim 25.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is not to be explained more closely through adescription of various embodiments, shown by way of example, and withreference to the drawings attached hereto.

FIG. 1 discloses a device according to a first embodiment of theinvention.

FIG. 2 discloses a device according to a second embodiment of theinvention.

FIG. 3 discloses a device according to a third embodiment of theinvention.

FIG. 4 discloses a set of blades of the device in FIG. 3.

FIG. 5 discloses a device according to a fourth embodiment of theinvention.

FIG. 6 discloses a set of guide vanes of the device in FIG. 5.

FIG. 7 discloses a device according to a fifth embodiment of theinvention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

FIGS. 1, 2, 3, 5 and 7 disclose different embodiments of a device forsealing a passage 1 through a wall 2 between a first space 3, which isarranged to contain a gas, and a second space 4, which is arranged tocontain a liquid. The wall 2 may form a stationary wall element of aship or of a stationary plant. A rotatable shaft 5, for instance apropeller shaft of a ship, extends in the passage 1 through the wall 2in such a way that a gap is formed, which extends around the shaft 5between the shaft 5 and the wall 2. The shaft 5 is rotatable around therotary axis x.

The device according to the invention includes a chamber 8, which isprovided between the first space 3 and the second space 4, and moreprecisely between the first space 3 and said gap of the passage 1. Thechamber 8 is annular and extends around the shaft 5. The chamber 8 isformed of a first limiting wall 11, a second limiting wall 12 and athird limiting wall 13. The three limiting walls 11, 12, 13 thus enclosethe chamber 8. The first limiting wall 11 and the second limiting wall12 extend substantially radially outwardly and in parallel to eachother. The third limiting wall 13 extends substantially coaxially withthe shaft 5 and between a radially outer end of the first limiting wall11 and a radially outer end of the second limiting wall 12. In the firstembodiment, the limiting walls 11, 12, 13 are fixed in relation to thestationary wall 2.

The device also includes a rotatable disc 14, which is fixedly arrangedon the shaft 5. The disc 9 extends substantially radially outwardly fromthe shaft 5 into the chamber 8 and divides the chamber 8 in a first partvolume 8 a and a second part volume 8 b.

Liquid from the second space 4 may thus via the passage 1 and said gapflow from the second space 4 into the chamber 8. Consequently, thechamber 8 will contain liquid. Furthermore, the device includesdifferent means, which are to be explained more closely in connectionwith the description of various embodiments and which are arranged toprevent liquid from flowing through the chamber 8 to the first space 3by forcing the liquid in the chamber 8 to rotate at a relatively highrotary speed, i.e. a rotary speed substantially exceeding the rotaryspeed of the shaft 5. The rotating liquid will thus form a rotatingliquid body in the first part volume 8 a of the chamber 8 between thedisc 14 and the first limiting wall 11.

According to the first embodiment disclosed in FIG. 1, said meansinclude a blade member 15, which includes a rotor member in the form ofa rotatable disc 16 and two sets of blades 17′, 17″. The first set ofblades 17′ are provided on one side of the rotatable disc 16 and thesecond set of blades 17″ are provided on the other side of the rotatabledisc 16. The rotatable disc 16 is provided on a cylindrical supportmember 18 of the blade member 15. The support member 18 is substantiallyconcentrically arranged around the shaft with regard to the rotary axisx. The rotatable disc 16 extends substantially radially outwardly in thechamber 8 from the support member 18 between the disc 14 and the firstlimiting wall 11 of the chamber 8 The first set of blades 17′ are thusturned towards the disc 14 and the second set of blades 17″ are turnedtowards the first limiting wall 11. The blade member 15 includes alsotwo sealing members 19′, 19″. A first such sealing member 19′ is turnedtowards the disc 14 and a second sealing member 19″ is turned towardsthe first limiting wall 11. The sealing members 19′, 19″ are designed insuch a way that they do not abut the disc 14 and the first limiting wall11, respectively, when the blade member 15 rotates, but will abutsealingly the disc 14 and the limiting wall 11, respectively, when theblade member 15 is still standing and liquid flows from the second space4 towards the first space 3.

The blade member 15 is according to the first embodiment rotatablycarried by the shaft 5 by means of a bearing member 21, which isprovided between and connected to the cylindrical support member 18 andthe stationary wall 2 via a substantially cylindrical projection 22 ofthe first limiting wall 11. The blade member 15 is rotated independentlyof the shaft 5 by means of a schematically disclosed drive motor 23,which via a drive belt 24 or any other power transmission member isconnected to the cylindrical support member 18. The drive motor 23 isthus arranged to rotate the blade member 15 at a rotary speed which ishigher than the rotary speed of the shaft 5, and in such a way create arotating liquid body in the radially outer part of the chamber 8. Thelevel of the rotating liquid is marked by the arrow 25.

Furthermore, the device is arranged to permit liquid to flow from thechamber 8, and more precisely from the second part volume 8 b of thechamber 8, to the second space 4. The second part volume 8 b is thuslocated between the disc 14 and the second limiting wall 12 forming awall portion 30 extending substantially radially outwardly from the gapmentioned above. The second part volume 8 b and the gap thus form anoutlet channel, which extends from a radially outer position at theperiphery of the disc 14 to a radially inner position in the proximityof the shaft 5.

FIG. 2 discloses a second embodiment where the blade member 15 forms thechamber 8 which thus is rotatable. It is to be noted that componentshaving substantially the same function have been provided with the samereference signs in the various embodiments. The chamber 8 in the secondembodiment thus is formed of a separate wall element 11, 12, 13, whichis rotatable around the shaft 5 independently of the rotation of theshaft 5 and which also includes a first limiting wall 11, a secondlimiting wall 12 and a third limiting wall 13. Also in this embodiment,the limiting walls 11 and 12 extend substantially radially outwardly andin parallel to each other, and the limiting wall 13 extendssubstantially coaxially with the shaft 5 and between a radially outerend of the limiting walls 11 and 12. The disc 14 extends substantiallyradially outwardly from the shaft 5 and into the chamber 8. A wallportion 30 extends substantially radially outwardly from said gap andsubstantially in parallel with the disc 14. The wall portion 30 isrigidly connected to the stationary wall 2. In the second embodiment,the second part volume 8 b of the chamber 8 and thus an outlet channelfor liquid from the radially outer part of the chamber 8 is formedbetween the disc 14 and the wall portion 30. In the second embodiment,the first part volume 8 a is formed partly between the first limitingwall 11 and the disc 14 and partly between the second limiting wall 12and the wall portion 30.

According to the second embodiment, the blade member 15 includes a firstset of blades 17′, which are arranged on the first limiting wall 11 andturned towards the disc 13, and a second set of blades 17″, which arearranged on the second limiting wall 12 and turned towards the wallportion 30. The first set of blades 17′ and the second set of blades 17″thus create a rotating liquid body in a radially outer part of therespective part volume 8 a, so that liquid extends to the levelindicated by the arrows 25.

The blade member 15 is according to the second embodiment rotatablycarried by the stationary wall 2 by means of a first bearing member 21′,which is arranged between and connected to the stationary wall 2 and asubstantially cylindrical projection 31 of the first limiting wall 11,and a second bearing member 21″, which is arranged between and connectedto the stationary wall 2 and a substantially cylindrical projection 32of the second limiting wall 12. A first sealing member 19′ is arrangedbetween the first substantially cylindrical projection 31 and the shaft5 in such a way that the first sealing member 19′ does not abut theshaft 5 when the blade member 15 rotates but only when the blade member15 is still standing. A second sealing member 19″ is arranged betweenthe second substantially cylindrical projection 32 and a substantiallycylindrical part 33 of the stationary wall 2. The substantiallycylindrical part 33 extends substantially concentrically from the wallportion 30 between the shaft 5 and the projection 32, wherein said gapis formed between the part 33 and the shaft 5. The sealing member 19″does not abut the part 32 when the blade member 15 rotates but only whenthe blade member 15 is still standing.

FIGS. 3 and 4 disclose a third embodiment where the blade member 15includes an annular rotor 40 of an electric motor. The blade member 10and the rotor 40 are provided in the chamber 8 and more precisely in thefirst part volume 8a. Also in this embodiment, the chamber 8 is formedby a first limiting wall 11, a second limiting wall 12 and a thirdlimiting wall 13, which thus enclose the chamber 8. In the same way asin the first embodiment, the three limiting walls 11, 12, 13 are rigidlyconnected to the stationary wall. The electric motor also includes astator 41, which has a winding 42 and which is arranged outside thechamber 8, and more precisely outside the first limiting wall 13. Theelectric motor may for instance be an asynchronous motor or a so-calledPMSM-motor. The blade member 15 is rotatably carried by the shaft 5 bymeans of a first bearing member 21′ and a second bearing member 22′. Nosealing members are disclosed in FIG. 3, but may for instance bearranged between the shaft 5 and the substantially cylindricalprojections 43, 44 of the limiting walls 11 and 22, respectively.

The blade member 15 includes a first set of blades 17′, which arearranged on the rotor 40 and turned towards the first limiting wall 11,and a second set of blades 17″, which are arranged on the rotor 40 andturned towards the disc 14.

FIG. 4 discloses schematically an example of a set of blades 17″ of thethird embodiment. The blades 17″ are arranged on an annular carrier 45which is mounted on the annular rotor 40.

FIG. 5 discloses a fourth embodiment of the invention. The chamber 8 isalso here formed by a first limiting wall 11, a second limiting wall 12and a third limiting wall 13. The three limiting walls 11, 12, 13 thusenclose the chamber 8 and are fixedly connected to the stationary wall2. In this embodiment, said means are arranged to supply liquid to thefirst part volume 8 a of the chamber 8 at such a speed and directionthat the liquid in the chamber 8 is forced to rotate at a rotary speedexceeding the rotary speed of the shaft 5. The means include a set ofnozzles 50 for said liquid supply. The nozzles 50 extend in asubstantially tangential direction into the chamber 8 seen in an axialsection. The liquid is supplied to the nozzles 50 by means of aschematically disclosed pump 51 via conduit members 52. A sealing member19 is arranged between the first limiting wall 11 and the shaft 5.

The outlet channel mentioned above, which partly is formed by the secondpart volume 8 b of the embodiments disclosed, is arranged to reduce thespeed of the liquid flowing from the chamber 8 to the second space 4.The outlet channel extends from a radially outer position at theperiphery of the disc 14 to a radially inner position in the proximityof the shaft 5. By said speed reduction a pressure recovery and thus alower energy consumption of the device is achieved. In order to furtherincrease the pressure recovery, guide vanes 60 of the type disclosed inFIG. 6 may be arranged in the outlet channel for conveying the liquidflowing from the chamber 8 to the second space 8 b. In the fourthembodiment, the guide vanes 60 are arranged on the second limiting wall12, forming a wall portion 30, and in the second embodiment on the wallportion 30. Also the device according to the first and third embodimentsmay be provided with such guide vanes.

FIG. 7 discloses a fifth embodiment, which differs from the otherembodiments by the fact that the chamber 8 includes three part chambers8′, 8″ and 8′″. Except for this difference, the construction and thefunction of the device according to the fifth embodiment in FIG. 7 issimilar to the construction and the function of the second embodiment inFIG. 2. The part chambers 8′, 8″ and 8′″ have been formed by means oftwo intermedient walls 71 and 72, which are provided with blades 17′″and 17″″, respectively, and which extend substantially radially inwardlyfrom the third limiting wall 13. Furthermore, the fifth embodimentincludes two rotatable discs 14′ and 14″ which extend into a respectivepart chamber 8′ and 8″, respectively, and two wall portions 30′ and 30″,which are provided with guide vanes 60′ and 60″, respectively, whichcorrespond to the guide vanes 60 in FIG. 2. The wall portions 30′ and30″ extend substantially radially outwardly from the cylindrical part 33and into a respective part chamber 8″ and 8′″, respectively. The centralpart chamber 8″ includes the second part volume 8 b and is thussubstantially identical to the chamber in FIG. 2, whereas the partchamber 8′ merely receives the disc 14′ and the part chamber 8′″ merelyreceives the wall portion 30″. It is to be noted that the chamber 8 mayinclude another number part chambers than appears from the embodimentsdisclosed. For instance, it may include the two part chambers 8′ and 8″,and the two rotatable discs 14′ and 14″, but merely one wall portion30′. Also other configurations are possible and especially it is to benoted that the chamber 8 may include more than three part chambersdisclosed.

The invention is not limited to the embodiments disclosed but may bevaried and modified within the scope of the following claims.

1-24. (canceled)
 25. A device for sealing a passage through a stationarywall between a first space, which is arranged to contain a gas, and asecond space, which is arranged to contain a liquid, wherein a rotatableshaft is intended to extend in the passage through the wall in such away that a gap is formed, which extends around the shaft between theshaft and the wall, a chamber being disposed between the gap and thefirst space and extending around the shaft, the device comprising: arotatable disc fixedly disposed on the shaft and extending outwardlyfrom the shaft into the chamber, wherein the chamber is arranged tocontain liquid; and means for forcing said liquid to rotate in thechamber at a rotary speed which substantially exceeds the rotary speedof the shaft.
 26. A device according to claim 25, wherein the forcingmeans includes means for providing rotation in the chamber between thedisc and the first space.
 27. A device according to claim 26, whereinthe forcing means includes a blade member operable to rotateindependently of the shaft.
 28. A device according to claim 27, whereinthe forcing means includes a drive member operable to rotate the blademember at a rotary speed which is higher than the rotary speed of theshaft.
 29. A device according to claim 27, wherein the blade member isrotatably carried by a bearing member which is connected to at least oneof the shaft, the disc, and the wall.
 30. A device according to claim27, wherein the blade member includes at least one set of blades whichare disposed in the chamber.
 31. A device according to claim 27, whereinthe blade member includes a rotor member which extends outwardly in thechamber.
 32. A device according to claim 31, wherein the blade memberincludes a first set of blades disposed on the rotor member and orientedtowards the first space, and a second set of blades disposed on therotor member and oriented towards the disc.
 33. A device according toclaim 31, wherein the rotor member includes a rotor of an electric motorhaving a stator disposed outside the chamber.
 34. A device according toclaim 27, wherein the blade member forms the chamber.
 35. A deviceaccording to claim 34, wherein the blade member includes a first set ofblades disposed on a first limiting wall of the chamber and orientedtowards the disc, and a second set of blades disposed on a secondlimiting wall of the chamber and oriented towards the first limitingwall.
 36. A device according to claim 25, wherein the forcing meanssupplies liquid to the chamber at a speed and direction sufficient toforce the liquid in the chamber to said rotation.
 37. A device accordingto claim 36, wherein the forcing means includes at least a nozzle forsaid liquid supply, wherein said nozzle extends in a substantiallytangential direction into the chamber.
 38. A device according to claim36, wherein the forcing means include a pump for providing said liquidsupply.
 39. A device according to claim 25, wherein the chamber includesseveral sub-chambers disposed between the gap and the first space andextending around the shaft, and two rotatable discs rigidly disposed onthe shaft and extending outwardly from the shaft into a respective oneof said sub-chambers, wherein each of said sub-chambers is arranged tocontain liquid.
 40. A device according to claim 39, wherein eachsub-chamber is disposed to permit a part of said liquid to flow into thesub-chambers and at least partly be retained for said sealing of thepassage.
 41. A device according to claim 25, wherein liquid flows fromsaid chamber to the second space.
 42. A device according to claim 25,further comprising a wall portion which partly defines the chamber andextends outwardly from the gap.
 43. A device according to claim 41,wherein the chamber between the disc and the wall portion forms anoutlet channel disposed to reduce the speed of the liquid flowing fromthe chamber to the second space.
 44. A device according to claim 43,wherein the outlet channel extends from a radially outer position at theperiphery of the disc to a radially inner position in proximity to theshaft.
 45. A device according to claim 43, further comprising guidevanes disposed in the outlet channel for conveying the liquid flowingfrom the chamber to the second space.
 46. A device according to claim45, wherein the guide vanes are disposed on the wall portion.
 47. Adevice according to claim 43, wherein the wall portion is rigidlyconnected to the wall.
 48. A method for sealing a passage through astationary wall between a first space, which contains a gas, and asecond space, which contains a liquid, wherein a rotating shaft extendsin the passage through the wall in such a way that a gap is formed,which extends around the shaft between the shaft and the wall, whereinthe method includes the steps of: providing a device including achamber, which is arranged between the gap and the first space andextends around the shaft, and a rotating disc, which is rigidly arrangedon the shaft and extends outwardly from the shaft into the chamber,wherein the chamber is arranged to contain liquid, and forcing saidliquid in the chamber to rotate at a rotary speed which substantiallyexceeds the rotary speed of the shaft.